
elementary set theory - Is $f^ {-1} (f (A))=A$ always true ...
2011年11月2日 · No. Not in general. Note that if you take the constant map $x\mapsto 1$ mapping $\mathbb{R}\to\mathbb{R}$ then $f^{-1}(f(\{0\}))=\mathbb{R}$. In fact, the equality …
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为何f^(-1)(f(A))不一定等于A,f(f^(-1)(B))也不一定等于B,在什么 …
我们可以证明,在映射f为单射的情况下, A=f^{-1}(f(A)) 。 证明: 由 f 是单射我们可以知道: x\in A\Longrightarrow f(x)\in f(A)\\ 所以若 x\in A,得到 f(x)\in f(A) ,有映射的定义我们可以得到 f^{ …
elementary set theory - Need help for proving that: $f(f^{-1}(A)) ⊆ …
If $y\in f(f^{-1}(A))$, then there exists $x\in f^{-1}(A)$ such that $f(x)=y$. Since $x\in f^{-1}(A)$, there exists $y'\in A$ such that $f(x)=y'$. Note that $y=y'$ by definition.
elementary set theory - Proof that $A \subset f^ {-1} (f (A ...
2016年9月4日 · According to $(1)$ here $f(x)\in f(A)$ can be replaced by $x\in f^{-1}(f(A))$. This results in:$$\forall x\left[x\in A\implies x\in f^{-1}(f(A))\right]$$ or equivalently: $$A\subseteq f^{ …
为什么f(f-1(x))=x? - 知乎
因为f-1 (x)很容易让人误会,让人以为这个x代表了f (x)的x,但其实这个x应该是f (x)=y中的y.因为反函数的 定义域 是原函数的 值域,所以其实f-1 (x)中的x其实是f (x)=y中的y,即f-1 (y),又因为f-1 …
Inverse Functions - Math is Fun
To convert Fahrenheit to Celsius: f (F) = (F - 32) × 5 9. The Inverse Function (Celsius back to Fahrenheit): f-1(C) = (C × 9 5) + 32. For you: see if you can do the steps to create that inverse! …
反函数 - 数学乐
所以把一个数值代入一个函数 f ,然后把结果代入其反函数 f-1 ,就会得到原来的数值: f-1 ( f(x) ) = x. 把函数的次序倒转也是一样: f( f-1 (x) ) = x
How to Find the Inverse of a Function: 4 Steps (with Pictures) - wikiHow
2024年11月29日 · A foundational part of learning algebra is learning how to find the inverse of a function, or f(x). The inverse of a function is denoted by f^-1(x), and it's visually represented as …
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What is an F-1 visa? A: An F-1 visa is a type of nonimmigrant visa for individuals who wish to pursue academic studies in the United States at a college, university, or other academic …
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